Egbert j



llnrrn STATEs ROBERT J. TILFORD AND HENRY M. REDEMANN, OF LOUISVILLE,KENTUCKY, ASSIGNORS TO THE REDEMANN-TILEORD STEEL COMPANY, OF SAMEPLACE.

MANUFACTURE OF STEEL.

SPECIFICATION forming part of Letters Patent No. 397,477, dated February5, 1889.

Original application filed J ly 25, 1888, Serial No. 281,018. Dividedand this application filed November 13, 1888. Serial No.

, 290,737. (No specimens.)

To all whom it may concern.-

Be it known that we, ROBERT J. TILFORD and HENRY M. REDEMANN, citizensof the United States, residing atLouisville, Jeffer- 5 son county,Kentucky, have invented new and useful Improvements in the Manufactureof Steel, of which the following is a specification.

Our invention relates to certain new and usefulimprovements in thetreatment of crude or low-grade steel to produce a refined or highgradesteel.

The most successful method of producing low-grade steel is that known asthe Bessemer process, described in his patent of 1855 but this product,as is well known,is suitable chiefly for railways, axles, and like uses,and

is totally unsuited for structures, machinery, and tool purposes, unlesspuddled, hammered, 2e and rolled, for the reason that in its normalstate it is too soft, and when hardened it becomes too hard and brittlefor the purposes stated. It was the recognition of these in herentdefects in the Bessemer and low and medium grade steel which led us tothe illvestigation of the subject which has developed our presentinvention, the object of which is the production at slight cost and aminimum degree of labor of a higher grade and more refined steel bytreating the Bessemer and other low and medium grade steel in suchmanner as to produce a molecular change from a coarse grain to a finegrain and silky fracture, to increase the tensile strength 5 andelasticity, toughness, and ductility, and to greatly increase thecarbon. \Ve have found from experience that, uniform results in allinstances flow from the treatment of metals having like properties.

With these ends in viewour invention 0011- sists in heating the metal tobe treated to a white heat, and then submerging the same in a bath ofglycerine and water in the proportion of three (3) ounces of glyeerineto one,-

half gallon water and allowing it to remain submerged until the changeis effected, which should be until the metal is substantially cool, oruntil such reduction of heat in the metal is made that it will no longertake up the gases generated by contact with the bath. Te have found insome instances that better results and effects are obtained by theaddition to the bath of glycerine and water of spirits of niter,aqua-ammonia, chloride of ammonium, sulphate of zinc, sulphate ofalumina, and ammonia; but to this last-named addition we lay no claimherein, as the same forms the subject-matter of a second divisionalapplication of our application, Serial No. 281,018, filed July 25, 1888,of which this application is the first division. Neither do we layherein. any claim to the broad idea of first heating low-grade steel toa degree of heat represented by white heat, and then subjecting themetal so heated to a liquid bath (in contradistinction to the dry orcementation process) in which hydrocarbon or similar gases are generatedby contact with the heated metal and bath, as this last-named matterforms the subject of our original application referred to.

' WVe of course do not wish to confine our-- selves to the exactproportions named, as they may be varied within reasonable limits, andyet produce the same general results but we have found from longexperience and repeated tests and experiments that the propertions givenproduce the best results.

It will also be understood that we do not wish to confine ourselves tothe exact degree of heat imparted to the metal, as that maybe variedslightly, so long as the results desired are obtained.

o have of course been unable to analyze the gases resulting from thecontact of the hotmetal body with the bath, but are led to be lieve thatthey constitute a hydrocarbon gas which has a strong ailinity for themetal, and that the latter, being in a heated state, is in such aphysical condition as to readily take 0 up or absorb such gas; but as tothe fact that the metal is highly improved we have no doubt whatever, ashas been demonstrated by all the well-known scientific and mechanicaltests.

It will be understood, of course, that when the treatment is applied adjaeent to the f urnaces where the low-grade steel is manufaotured theingots may be treated without reheating, and thus the expense of suchreheating is avoided. After the metal has been subjected to thetreatment in the bath of glycerine and water it is allowed to cool inthe ordinary manner, and it may afterward be subjected to any ordinaryhardening or tempering process, and the temper may, if necessary, bedrawn and again restored without at all affecting the other propertiesacquired from the bath.

WVe are of course aware that the quality of Bessemer and other low andmedium grade steel may be improved by what is known as the dry orcementation process, which requires a large expenditure of skilled laborand great length of time, and that, too, without always securing uniformand satisfactory results.

WVe desire it to be distinctly understood that we lay no claim to thebroad idea of increasing the quality of steel by subsequent treatment,as that has been heretofore done, especially by what is known as thecementation process, which 'may be termed a dry process, our inventiondiffering from such process in the particular that it requires a periodof time amounting to a small percentage of the time required in thecementation or dry process, and is in contradistinction to such processessentially a liquid or wet process, the former requiring many days,while the latter involves only a few minutes.

As before stated, we wish it to be understood that the chief feature ofour process involves the employment of a bath of glycerine and water,for in the use of these two bodies we accomplish desirable and improvedresults; but the addition to the glycerine and water of spirits ofniter, aqua-ammonia, chloride of ammonium, sulphate of zinc, andsulphate of alumina and ammonia produce bet ter and enhanced results;hence we do not wish to confine ourselves to the use of abath embodyingall the bodies named.

Our invention or process is distinguished from processes for temperingsteel in oil in that by our process the nature and the physicalconstruction of the metal are completely changed, whereas the temperingof steel in oil, as practiced by some processes, simply tempers themetal more slowly than is done by tempering in water and otherproperties, leaving the metal less hard, but somewhat tougher thanwater-tempered material. The changes caused by the oil-tempering processare merely temporary, and do not change the physical or granularconstruction of the metal, and such changes as are caused thereby can bereadily neutralized by reheating and allow ing the metal to cool. The chnges caused by treatment by our process are permanent, and cannot beremoved by any known treatment or process without entirely destroyingthe steel properties of the metal by burning.

By our invention we greatly increase the tensile strength andelasticity, and yet do not destroy the percent. of reduction orductility, while with ordinary tempering the tensile strength andelasticity are greatly increased, but the per cent. of reduction andductility is Very much impaired.

NVhat we claim as new, and desire to secure by Letters Patent, is

The process herein described for converting lower-grade steel intorefined or highergrade steel, which consists in heating the metal to betreated to a white heat, and then submerging the heated metal in aliquid bath .of glycerine and water in the proportion of three ounces ofthe former to one-half gallon of the latter, substantially ashereinbefore set forth.

In testimony whereof we have hereunto set our hands in the presence oftwo subscribing witnesses.

ROBERT J. TILFORD. HENRY M. REDEMANN.

WVitnesses:

HENRY J. TILFORD, DAVID BARKLEY.

